21 



2.2.2.2 Priority Pollutant Metal Analyses 



Twenty-three marine sediment samples were analyzed for priority pollutant metals. 

 Antimony (Sb), beryllium (Be), cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), 

 silver (Ag), and zinc (Zn) were analyzed by inductively coupled argon plasma emission 

 spectrophotometry (ICP). Arsenic (As), lead (Pb), selenium (Se), and thallium (Tl) were 

 analyzed by graphite furnace atomic adsorption techniques (GFAA). Mercury (Hg) was 

 analyzed using cold vapor atomic adsorption (CVAA); all metals were analyzed using 

 standard EPA procedures (Table 2-1; EPA 1986). Three QC samples were analyzed with the 

 samples: a method blank, a blank spike, and a blank spike duplicate sample. Sample data 

 were evaluated using protocols developed by the EPA CLP (EPA 1988b). 



Samples analyzed for all metals except for Hg were digested 181 days after sample 

 collection, and analysis was conducted approximately 28 days later (Table 2-2). Mercury 

 samples were digested 177 days after sampling and analyzed the following day. EPA 

 guidelines suggest a maximum holding time for metals analyses of 6 months, and 28 days for 

 Hg. Due to the excessive holding time for the Hg samples, Hg results were qualified as 

 estimated, and given the qualifier code J for detected values and UJ for undetected values. 



The metals sample method blank was below detection for all metals except for Zn 

 (4.3 ppm). All samples contained zinc in concentrations greater than 5 times the 

 concentration detected in the method blank, so no qualifications were necessary (EPA 

 1988b). 



A blank spike and a blank spike duplicate sample were analyzed for metals as an 

 evaluation of laboratory accuracy and precision. All spike recoveries were well within 

 control limits (84-105%) except for one duplicate spike recovery of Ag. Precision, also, was 

 acceptable as all RPDs were < 10% except for the silver duplicate RPD. Because of the low 

 recovery of one Ag sample, all non-detects of Ag were qualified as estimated, and assigned a 

 qualifier of UJ. The laboratory stated in the Quality Assurance Review that the low silver 

 recovery is being investigated. The accuracy and precision of all metals data except for Ag 

 were considered acceptable. 



2.2.2.3 Polynuclear Aromatic Hydrocarbon (PAH) Analyses 



PAHs were analyzed using EPA protocols. Twenty-three marine sediment samples 

 were analyzed with four accompanying QC samples: a method blank, a standard reference 

 material (SRM) sample, a blank spike, and a blank spike duplicate sample. Sample data 

 were evaluated using protocols developed by the EPA (EPA 1988a). 



Samples analyzed for PAHs were extracted 149-156 days after sample collection, and 

 analyzed 7-29 days after sample extraction. EPA guidelines suggest maximum holding times 



Sediment Core Chemistry Data Summary from the MQR Mound, August and December 1991 



